Abstract:Our recent work [1, 2] based on the Schwinger-DeWitt method of background
fields fills the gap which existed in describing the asymptotic expansion
of the one-loop effective action with virtual heavy fermion masses. This
approach faithfully mirrors the vacuum structure of the underlying theories.
Moreover, for the case of taking into account the 't Hooft six quark flavor
mixing interaction, we have shown that the quantum fluctuations, which
had not been considered previously , lead to a different scenario for constituent
quark masses and related condensates in QCD.